But there was a phrase that Cantor mentioned that stood out for me. The frequently-confused Republican leader said that if voters backed the GOP in November, his party would offer “responsible, adult leadership.”

Now, of all the things Republicans have to offer the electorate, perhaps no three words in the English language are less appropriate than “responsible, adult leadership.” As should be abundantly clear by now, today’s GOP officials approach their responsibilities and substantive discourse with all the maturity of a child. A young child. A young, slow child. A medicated, young, slow child who’s easily distracted and hasn’t learned social norms about honesty.

Jacob Weisberg notes in his latest piece that there were responsible, adult leaders in the Republican Party in the not-too-distant past, but they’ve gone missing.

Do you remember the Responsible Republicans? In the 1980s, small herds of them still roamed freely around Washington. In 1982, they stampeded over Ronald Reagan’s veto of the largest tax increase in history to mitigate the fiscal harm of his 1981 tax cut. In 1983, they converged on Capitol Hill to pass a package of tax increases and benefit cuts recommended by the Greenspan Commission to keep Social Security solvent. In 1986, they followed Wyoming Sen. Alan Simpson to pass bipartisan immigration reform legislation by a large majority. In 1990, several were spotted with President George H.W. Bush (the Responsible one) at Andrews Air Force Base, conspiring to reduce the deficit.

After the Andrews summit, however, glimpses of them outside captivity became increasingly rare. With their habitats in the Northeast, Midwest, and Pacific Northwest under threat and their natural predators on the rise, the status of the species moved from “threatened” to “endangered.” Though occasionally spotted on the rocky shoals of Maine’s Penobscot Bay and in beach houses up and down the California coast, they now rarely emerge from the wilderness. During the health care battle, President Obama was unable to find a single Responsible Republican to serve as a mascot. There continue to be rumors of the Double R’s return around issues such as immigration, financial reform, and climate change. Yet we have now gone several years without a confirmed sighting.

The point of Weisberg’s piece was to identify the moment that sent the GOP grown-ups into permanent exile. The Slate editor points to Bill Kristol’s 1993 health care strategy memo — kill reform at all costs, regardless of merit, Kristol advised, and refuse to cooperate in good faith — as the “crucial” turning point for contemporary Republicans, which helped shape the party’s approach to governing ever since. That sounds about right to me.

But regardless of the origins, the consequences are the same.

In 2010, Republicans choose not to know anything about public policy, can’t engage in an honest debate, reflexively oppose anything Democrats support (including GOP ideas), and reject responsibility for the spectacular failures they created while in the majority.

Cantor is promising “responsible, adult leadership”? From whom, exactly? When was the last time a Republican leader said something intelligent and accurate about any area of public policy? When was the last time the GOP acted in a responsible fashion during a substantive debate? When was the last time the nation saw so much as a glimmer of maturity from any member of the party leadership?

Weisberg concluded, “The rise of hyperpartisanship is not one of those problems for which the left and right are equally to blame. Democrats, who like legislating better than Republican do, and who have seldom had the GOP’s ability to march in lockstep, still instinctively prefer to work on a bipartisan basis. They continue to hope, against the odds, that [Responsible Republicans] will escape extinction and one day provide partners for them again.”

It seems clear to me that won’t happen unless Republicans suffer some additional, severe electoral humiliations. On the contrary, if the GOP fares well in the midterms, the party’s leaders and rank-and-file members will assume the way to get and keep power is to avoid responsible, adult leadership altogether.